Data storage disk files typically utilize one or more rotatable disks having a magnetic recording surface on each side of each of the disks and transducers mounted on sliders for reading and/or writing data on the magnetic recording surfaces. Each slider is mechanically supported on a suspension to maintain the slider in a close transducing relationship with respect to the corresponding magnetic recording surface. The suspension is attached to an actuator for moving the transducer radially over the disk to a desired track and maintaining the transducer over the track centerline during read or write operations.
The suspension typically loads, or provides a force against the slider, to counter the force of the air bearing between the slider and the magnetic recording surface of the rotating disk. The force is typically provided by a load beam which is mounted on an arm of the actuator and provides a spring action which biases the slider toward the surface of the disk. A flexure and gimbal is typically attached to the distal end of the load beam, and supports the slider, which is mechanically supported by epoxy bonding. The flexure and gimbal provide controlled flexibility in pitch and roll motion of the slider relative to its direction of motion on the rotating disk recording surface and provide resistance to yaw.
One type of suspension is an integrated lead suspension which incorporates a laminated conductive lead structure for connecting the transducer and the disk drive read/write electronics. An example of a laminated structure and the method of attaching the conductive leads to the transducer is illustrated in U.S. Pat. No. 4,761,699. The laminated structure comprises a structural layer of stainless steel, an insulating layer of polyimide formed on the structural layer, and a patterned conductive layer of etched copper alloy formed on the insulating layer. The described process for attaching the conductive layer electrical leads to the transducer is complicated and requires both passivation of the conductive layer, followed by the creation of vias through the passivation, and, most importantly, requires that it be heated in a furnace with the slider and transducer in order to reflow solder bumps. The alignment of the pads is difficult to accomplish and the heat of the furnace must be controlled precisely so as to not affect the transducer. The temperature control is possible with an inductive transducer, but is critical when an MR (magnetoresistive) read transducer is utilized and it is easy to destroy the MR transducer.
An alternative approach is described in U.S. Pat. No. 5,530,604, which forms solder bumps on both the transducer termination pads and the conductive leads of the patterned conductive layer of the laminated suspension. One or both of the solder bumps are then flattened and the slider is then attached to the suspension. A laser is used to heat the solder bumps so that they expand back into a spherical shape from the flattened shape upon reflow such that they make contact with each other. There are three drawbacks to this approach. First, the two sets of solder bumps must be closely aligned in order to insure a robust, reliable reflow process. Second, the solder must be applied to the transducer termination pads at the wafer level and the wafer processed through the slider fabrication without damage to the solder, a task that is difficult to achieve. Third, the flattening of the solder bumps requires considerable force, which force is difficult to accomplish when applied to the transducer termination pads.
What is needed is the provision for substantial tolerance in the alignment of the transducer termination pads and the leads of the patterned conductive layer and still make a reliable connection.